Hot-air liquid-fuel furnace



COLD AI R RETURN F. M. WILSON, SR

HOT-AIR LIQUID-FUEL FURNACE- Filed July 9, 1956 WARM AIR lliiik lllllll I T V //////l July 7, 1959 INVENTOR.

k 1 g I Fred Mwllson ,Sr 21 Attor'ne g s FIQHS United States Patent HOT -A1R LIQUID-FUEL FURNACE Fred M. Wilson, Sr., Chicago, Ill., assignor of twenty-five percent to Paul E. Petrie and twenty-five percent to Bernard Braverman Application July 9, 1956, Serial No. 596,480

2 Claims. (Cl. 126110) This invention relates to an improved hot-air furnace particularly adapted for efficient burning of liquid fuel and utilization of the energy thereof.

A major object of the invention is to provide a furnace for utilizing fuel such'as light hydrocarbon oil, wherein the combustion air is controlled in its flow path to provide maximum efficiency of combustion and superior heat-transfer properties asbetween the gaseous combustion products and the circulating air to be heated.

Another important object of the invention is to provide anovel burner structure wherein the fuel is burned in a flat dish-like burner plate in the presence of controlled combustion air, the'burner structure combining the advantages of highly efficient combustion at full output with substantially out-proof pilot operation during stand-by periods. r

4 Still anotherobject of the invention is to provide a hotair furnace wherein the combustion air is placed in an initially spiral path of motion before it enters the burner chamb'erand is maintained in. the same generally spiral path of movement during the. combustion phase and during the following heat-exchange phase in which the combustion gases give up the major part of their heat content to the circulating room air to be heated.

Other objects and advantages of the invention will appear from the following detailed description of a typical embodiment. In thefollowingdescription of a typical embodiment of the invention, reference-will be-had to the appended drawing, in which Figure 1- is a diagrammatic side view, partly in section, of atypical furnace in accordance with the invention, Fig. 2 is a fragmentary view in horizontal section of a portion of the Fig. l furnace, bringing out clearly the positional relationship of certain important components thereof, and Fig. 3 is a sectional view of the burner proper.

As may be noted from Fig. l, the furnace is enclosed within an outer housing which may be made of any suitable material having heat-insulating properties. Typically, the outer husing 10 may be formed of inner and outer sheet-metal layers with insulating material between them, or it may be built up of brick, cement block, or other such material.

The housing 10 is perforated on its top surface to provide a warm-air outlet passage 11 and a cold-air return passage 12.

The interior of housing 10 is divided by a transverse wall 13, forming a main heat-exchange zone 14 and a pre-heater zone 15.

The heat-exchange zone 14 is further divided by means of a metal inner housing 16 to define a fire box 17, which contains the burner 18 and the baffle structure 19. Combustion gases formed within the fire box 17 pass outward through a flue 21 into a pre-heater 22 and thence into discharge flue 23.

The pre-heater 22 may be conventional in construction; it has the function of utilizing a portion of the heat in the 2,893,374 Patented July 7, 1959 ice 2 flue gases to pre-heat the inlet air coming downward from the cold-air return 12.

A conventional air-circulating blower 24 is mounted below the pre-heater 22 for the purpose of forcing the inlet air into the heat-exchange zone 14 via the passageway 25. After leaving passage 25 the inlet air circulates upward around the wall 16 of the fire box, where it is heated by heat exchange with the combustion gases through the metal wall 16, and the air thus heated passes outward through the warm-air duct 11 into the space (not shown) to be heated by the furnace.

At the bottom portion of the fire box I provide a blower 26 which forces air for combustion into the burner chamber 27, the chamber 27 being defined by the lower portion of fire-box wall 16 and a horizontal partition 28 which is mounted in the lower part of the fire box. Depending from partition 28 is a baffle 29; the blower 26 and the baffle 29 are disposed so that the air from blower 26 strikes bafile 29 at an angle operative to swirl the combustion air in a circular path around the chamber 27.

Centrally mounted within the burner chamber 27 is the burner proper 18, comprising a generally cylindrical element as shown, closed at the bottom by a plate 31 and at the top by a plate 32. Plate 32 is centrally apertured and provided with a raised rim 33 which connects the interior of the burner 18 with the interior of the fire box above partition 28.

The side walls of burner 18 and of rim 33 are provided with a large number of small air-inlet apertures 34 symmetrically disposed around their respective surfaces.

A fuel plate 35, having a flat bottom and a slightly raised peripheral lip, is mounted above the center of plate 31, the center of plate 35 being provided with an aperture in which a fuel-inlet pipe 36 terminates. The inlet end of fuel pipe 36 is connected to a fuel pump 37, which may be of the conventional thermostatically controlled type, in which the quantity of fuel fed is regulated electrically in response to temperature of a thermostat situated in the space to be heated. Such devices are conventional in the space-heating art and do not of themselves form any part of the present invention.

Similarly, the operation of blower 26 will normally be controlled in the same manner.

symmetrically disposed in the fire box 17 above the partition 28 is the baffie apparatus 19 heretofore mentioned, which comprises a conical flame spreader 41 equipped with a plurality of curved fins 42, shaped to guide the combustion gases as they rise from the burner proper and to cause them to swirl around the inner surface of the fire box in intimate contact with the metal wall 16.

Above the flame spreader is a frusto-conical baffle 43, mounted on a plurality of spider-like projecting arms 44 and operative to guide the combustion gases into the topmost part of the fire box 17 while maintaining their swirling path of movement.

One or more suitable access passages such as passage 49, closed by door 51, may be provided to yield easy access to the interior of the fire box for cleaning and maintenance purposes. For the same purpose, the plate which forms the top of inner housing 16 may be made removable.

In operation, a very small amount of fuel oil will be supplied to the burner dish 35 through pipe 36 to provide a pilot flame, which will burn at all times. This pilot flame will generate suflicient heat to keep the dish 35 hot. When the thermostatic control calls for heat output from the furnace, the rate of fuel passage through pipe 36 will be greatly stepped up and, at the same time, blower 26 will begin supplying a greatly increased quantity of air for combustion.

The swirling air circulating in the portion of the fire box below partition 28 will enter the burner chamber 3 through theJ-apertures- 34 and will there react with the fuel oil--in-the dish 35, 1 providing a swirling flame-which will substantially fill the burner chamber 18 and pass upward through the rim 33 "into the portion of the fire box 17-abovepartition 28. In thatregionthe combustion gases, aided in their swirling movementby the cone-41 and the fins 42, will circle in intimate contact: with :the wall; ;16 upward through I the fire box, past the frustoconicalbaffie 43 and ultimately out-of-the firebox through flue 21. -In the course of their-circuitousjourney through the' fi-reboxvl7, the combustion gases give up a major portion of their heat' by heatvexchange, through wall 16, to the upwardly" flowing air in :thea-nnular'region between-wall :16 and: the outer housing :10. additional part of the heat-remainingin'the combustion gases-when they leave the fire box 17 is used :in, pro-heating the air flowing downward from-eold-airreturn 12.

The structure of my burner-proper, comprising the perforated member 18 and :the' dished fuel plate-35 contributes importantly :to 1 the cflicient operationof my furnace, since it permits a wide range of burning rates without sacrifice of combustion efliciency. In operation, :the plate 35 is sufliciently hot to vaporize the fuel almost instantly on contact and thereby achieve complete combustion even at high rates of fuel feed.

While I do not wish to limit-myself to any particular dimensions or proportions inthe construction of my invention, I have found the following illustrative dimensions to be excellent in furnaces designed for heating small dwellings:

Plate 35-4" diameter with A lip Burner element 18-10" diameter and 8" height Rim 33-5 diameter, 1" height Fire box.17l8" diameter.

'In practical operation, furnaces made according to my invention have proved to be impressively superior to conventional liquid-fuel space heaters. Superior combustion efficiency and heat exchange-have resulted in substantial fuel savings, and, moreover, my novel burner design provides superior pilot dependability combined with eflicient combustion from the first instant that heat in quantity is called for by the thermostatic control 'apparatus. This last-mentioned advantage results in large part, I believe, from the fact that fuel plate 35 is kept hot by the pilot flame duringstand-by periods.

It will be understood that persons skilled in the art will be able to make many changes and variations in the structure shown without departing from the spirit of my invention. The embodiment of my invention herein the scope of my invention 4 described should therefore be considered illustrative only, .being .determined from.. the appended claims.

I claim:

1. In a. hot-air, liquid-fuel space heater, the combination comprising an elongated cylindrical fire box mounted with its long dimension vertically disposed, inlet means near the bottom of said fire box for introducing combustion airither'ein with artangential component of velocity, whereby a swirling motion within said.fire box is impartedto said combustion-air, a generally cylindrical burner coaxially' disposed in said firebox near .itslower end, said burner comprising a dished plate mounted within a cylindrical perforated :shield, said shield being relieved in a zone.directly abovesaid .plate and being otherwise substantially closed save for' a plurality of airinlet perforations in its walls, said perforations being proportioned and positioned to permit said swirling combustion air to enter said burner without losingtits 'said swirling ;motion, a transverse partition in said fire" box closing off the space between its side walls and the relieved Zone of said shield, means for feeding liquid .fuel into said-dished plate, baffle means mounted in said fire boxabove said partition operative to guide combustion products risingthrough said relieved zone into a swirling circumferential path around the side walls of said fire box in the same direction as the swirling motion of said combustion air, exit means for said combustion products near the top =0f said fire box, air-passage means outside said fire box, and means for circulating air from the space to be heated through said air-passage means for heating the same by heat exchange through the walls of said firebox,:said baflle being formed in the shape of an inverted cone and provided with a plurality of curved fins proportioned and positioned on said bafi le to givethe combustion gases the :same direction .of rotation as .said combustion air.

2. A :space heater as defined .in claim 1 wherein said conical bafile is surrnountedby a second bathe, saidsecond bafile having a frusto-conical conformation converging upwardlyin said fire box.

References Cited in the file of this patent UNITED STATES PATENTS 1,569,967 Danielsen Jan. 19, 1926 1,651,628 Pecker Dec. 6, 1927 2,257,834 Behee Oct. 7, 1941 2,287,361 Suchland June 23, 1942 2,389,264 Livar Nov. 20, 1945 

